This then is the first principle I establish in the science of human nature; nor ought we to despise it because of the simplicity of its appearance.  For it is remarkable, that the present question concerning the precedency of our impressions or ideas, is the same with what has made so much noise in other terms, when it has been disputed whether there be any innate ideas, or whether all ideas be derived from sensation and reflexion.  We may observe, that in order to prove the ideas of extension and colour not to be innate, philosophers do nothing but shew that they are conveyed by our senses.  To prove the ideas of passion and desire not to be innate, they observe that we have a preceding experience of these emotions in ourselves.  Now if we carefully examine these arguments, we shall find that they prove nothing but that ideas are preceded by other more lively perceptions, from which the are derived, and which they represent.  I hope this clear stating of the question will remove all disputes concerning it, and win render this principle of more use in our reasonings, than it seems hitherto to have been.

SECT.  II.  DIVISION OF THE SUBJECT.

Since it appears, that our simple impressions are prior to their correspondent ideas, and that the exceptions are very rare, method seems to require we should examine our impressions, before we consider our ideas.  Impressions way be divided into two kinds, those Of sensation and those of reflexion.  The first kind arises in the soul originally, from unknown causes.  The second is derived in a great measure from our ideas, and that in the following order.  An impression first strikes upon the senses, and makes us perceive heat or cold, thirst or hunger, pleasure or pain of some kind or other.  Of this impression there is a copy taken by the mind, which remains after the impression ceases; and this we call an idea.  This idea of pleasure or pain, when it returns upon the soul, produces the new impressions of desire and aversion, hope and fear, which may properly be called impressions of reflexion, because derived from it.  These again are copied by the memory and imagination, and become ideas; which perhaps in their turn give rise to other impressions and ideas.  So that the impressions of reflexion are only antecedent to their correspondent ideas; but posterior to those of sensation, and derived from them.  The examination of our sensations belongs more to anatomists and natural philosophers than to moral; and therefore shall not at present be entered upon.  And as the impressions of reflexion, viz. passions, desires, and emotions, which principally deserve our attention, arise mostly from ideas, it will be necessary to reverse that method, which at first sight seems most natural; and in order to explain the nature and principles of the human mind, give a particular account of ideas, before we proceed to impressions.  For this reason I have here chosen to begin with ideas.